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How to Make Good Waterproofed Concrete 

With Medusa Waterproofed Gray Portland Cement 

Medusa Portland Cement Company • 1000 Midland Bldg., Cleveland, 0. 

Sales Oiiices: New York, N. Y. • Chicago, 111. • Grand Rapids, Mich. • Manitowoc, 
Wis. • Cleveland, O. • Pittsburgh, Pa. • Washington, D. C. • York, Pa. • Toledo, O. 

Copyright Medusa Portland Cement Co. 1939 

Printed in U. S. A. 

Why the Name Medusa? 

When Perseus was grown up, Polydecies sent him io atiempi the conquest of the 
Gorgon Medusa, a terrible monster who had laid waste the country. She had once 
been a maiden whose hair was her chief glory, but as she dared to vie in beauty with 
Minerva, the Goddess deprived her of her charms and changed her ringlets into hissing 
serpents. She became a monster of so frightful an aspect thai no living thing could 
behold her without being turned into stone. All around the cavern where she dwelt 
might be seen the stony figures of men and animals that had chanced to catch a 
glimpse of her and had been petrified at the sight. ♦ Perseus, favored by Minerva and 
Mercury, set out against the Gorgon and approached first the cave of the three Graeae. 
Here the three old crones with their single eye sat bemoaning their lot. Snatching the 
eye, Perseus compelled the Graeae, at the price of its restoration, to tell him how he 
might obtain the Helmet of Hades, thai renders its wearer invisible, and the winged 
shoes and pouch that were necessary. With this outfit, to which Minerva added her 
shield and Mercury his knife, Perseus sped to the hall of the Gorgons. In silence sat 
two of the sisters— but the third paced about the hall moaning and shrieking in despair 
because the golden tresses of her hair were moved by writhing snakes from side io 
side. This was Medusa. While she was praying the gods to end her misery, or, as some 
say, while she was sleeping, Perseus approached, and, guided by her image reflected 
in the bright shield which he bore, cut off her head and so ended her miserable ex- 
istence. The head itself he bestowed upon Minerva, who bore it afterwards upon her 
aegis, or shield. That is the story of Medusa. ♦ Years ago when our company was in 
search of a good brand name, Medusa, the name of the fabled woman of Greek 
mythology whose glance turned living creatures to stone was selected as most ap- 
propriate for our cement products. What could better symbolize the modern magic by 
which Medusa Portland Cement creates great edifices and engineering works as solid 
as the native rock? We believe that few products are so significantly named. And 
so the name Medusa, applied to products made by the Medusa Portland Cement 
Company of Cleveland, lives today and her magic power survives most beneficently, 
atoning for her malevolence by creating useful structures for the benefit of mankind. 

Duke University, Durham, North Carolina 

Horace Trumbauer, Philadelphia, Architect A. C. Lea, Chief Engineer 

E. H. Clement Co., Charlotte and Durham, N. C, Stone Contractors 

Medusa products furnished by W. C. Lyon Co., Durham, N. C. 

Medusa Waterproofed Gray Portland Cement and Medusa Waterproofed White Portland Cement were used in the construction of this large project. 

WHY Concrete, stucco and masonry, including mortar, should 
be waterproofed during the original construction 

• For centuries past and to come, concrete has 
been and will continue to be one of man's most 
dependable and useful building materials. This 
dependence in concrete is due to its flexibility 
in application and its strength and ability to with- 
stand the most severe construction conditions. 

Concrete is usually exposed to water and mois- 
ture, ground acids and alkalies as well as acid 
fumes in the air. It is subject to freezing and thaw- 
ing actions brought about by changes of tem- 
perature and the elements. 

Because of its naturally sturdy, strong character, 
concrete withstands these severe conditions bet- 
ter than most other types of construction materi- 
als. However, even the naturally long life of 
concrete can be greatly extended if it is water- 
proofed for protection. 

Waterproofed concrete means concrete that suc- 
cessfully repels water at the surface. Water- 
proofed concrete should not be confused with 
water tight concrete. In the latter case the con- 
crete may absorb water but the water does not 
necessarily travel completely through the con- 
crete itself. 

The more water concrete absorbs, the sooner the 
concrete will need maintenance or replacement. 
Water absorbed into tiny crevices or cracks is 
subject to freezing. Freezing water expands with 
a terrific force which widens these liny pores 
and crevices and deterioration starts in. If con- 
crete is waterproofed, the water is repelled at the 
surface and thus the deteriorating action caused 
by freezing of the absorbed water is prevented. 

WATER DAMAGE - The absorption of water 
through a concrete wall or through the mortar 

joints in masonry construction may cause con- 
siderable damage. Most frequently this damage 
consists of the ruining of plaster and interior 
decorations and damaging interior wood mold- 
ing, floors, linoleum, carpets, etc. 

MAINTENANCE— The maintenance of concrete, 
stucco or masonry walls when once absorption 
of water takes place is expensive and continu- 
ous. Thai's why it is highly important that these 
types of construction should be waterproofed 
during the original construction. A few addi- 
tional dollars spent for waterproofed concrete, 
stucco and mortar at the time of building means 
only a very small percentage added to the cost, 
whereas unwaterproofed construction thai ab- 
sorbs moisture may be the cause of spending 
in repairs and damage, many, many times the 
cost of waterproofing during construction. It is 
always less expensive to waterproof during 

SANITATION - Interior walls and floors that 
have become damp through lack of waterproof- 
ing give rise to musty odors that frequently 
contaminate merchandise and produce mildew 
and rust, and oftentimes are conducive to disease. 
For these reasons, public health officials do not 
approve damp conditions in buildings used for 
habitation or work. 

In the pages of this book we have covered the 
use and specifications for waterproofing many 
specific types of construction with Medusa 
Waterproofed Gray Portland Cement. This 
cement is mixed and used the same way as regu- 
lar Gray Portland Cement and meets and ex- 
ceeds all specifications for regular Gray Port- 
land Cement. 

WATERPROOFED Cement has these advantages 

Medusa Waterproofed Gray Portland Cement is 
a true waterproofed cement. That is, it is our 
regular Medusa Gray Portland Cement to which 
has been added the correct amount of Medusa 
Waterproofing, mechanically ground in during 
the process of manufacture, thereby insuring a 
complete distribution of the waterproofing 
throughout the cement. This means that Medusa 
Waterproofed Gray Portland Cement will give 
the maximum waterproofing value. The use of 
a waterproofed cement— that is a cement with 
the correct amount of waterproofing added at 
the mill during the process of manufacture-has 
a number of decided advantages over adding a 
waterproofing material to the cement at the time 
of mixing on the job. 

The contractor or builder likewise benefits from 
the use of waterproofed cement in that he, too, 
has less supervision and one less material to 
handle on the job. Medusa Waterproofed Gray 
Portland Cement requires no special effort to 
handle, since it is used the same as regular Gray 
Portland Cement. 

The most vitally interested party, however, is 
the owner and he should insist that Medusa 
Waterproofed Gray Portland Cement be used in 
his work. The use of this cement assures him of 
permanent waterproofing at a very small ad- 
ditional cost. 

Let us emphasize that it does not require any 
special knowledge to use Medusa Waterproofed 
Gray Portland Cement. Anyone who knows how 


chool Winston-Salem, North Carolina Harold Mackhn, Architect 

Medusa Waterproofed Gray 

Today most architects prefer a waterproofed 
cement because it eliminates the supervision 
necessary to insure the proper amount of water- 
proofing is used. The specification, therefore, of 
Medusa Waterproofed Gray Portland Cement 
eliminates the human-element hazard always 
present when waterproofing agents are added 
on the job. This means the resulting concrete is 
sure to be permanently waterproofed and the 
owner satisfied. 

F. L. Blum & Co., Contractors 
Portland Cement used. 

Standard Supply Co., Dealer 

to make good concrete can make good water- 
proofed concrete with Medusa Waterproofed 
Gray Portland Cement. There is no question as 
to the waterproofing efficiency of this cement. 
It has a service record of 32 years, having been 
used in countless jobs below and above grade 
under unusually severe conditions, and has 
been thoroughly tested in concrete as well as in 
mortar for laying up brick, tile, concrete blocks, 
stone, etc. 

PROVING the value of Medusa Waterproofing 

Three concrete blocks— left made with regular cement, center with Medusa Waterproofed Gray 
Portland Cement and right with Medusa Concentrated Waterproofing Paste— were placed in pans 

which were filled with water. 

In 15 minutes water has risen by capillary attraction half-way up the unwalerproofed block. The 
Medusa Waterproofed blocks show no rise because the water was repelled at the surface of the concrete. 

At the end of an hour the unwalerproofed block was wet all over and the Medusa Waterproofed 
blocks were dry, proving the efficiency of Medusa Waterproofed Gray Portland Cement and Medusa 
Concentrated Waterproofing Paste in slopping absorption of water at the surface of the concrete blocks. 

ESSENTIALS of good waterproofed concrete 

CONCRETE-Concrete is a mixture of porlland 
cement, water and mineral aggregates placed 
in a plastic condition but hardening soon after, 
due to the process known as hydration of the 
cement. Since concrete is placed in a plastic 
condition, it cannot be tested for quality at the 
time of fabrication. However, by proper control 
of the proportioning, mixing and placing to- 
gether with the subsequent curing, it is possible 
to produce concrete of any quality to meet the 
requirements of the work. 

The fundamental requirements of hardened con- 
crete are strength, waterproofness, durability 
and economy. Fresh concrete must be workable, 
that is, it must be of such consistency and physi- 
cal make-up that it can be readily placed in the 
form without segregation of the materials and 
without requiring an excessive amount of spad- 
ing to completely fill the form. Uniformity in the 
fresh concrete is necessary to secure durability 
of concrete, to facilitate handling and placing 
and to obtain uniformity in the complete struc- 
ture. It is particularly important where water- 
proofness is required. 

STRENGTH— Most concrete design is based on 
compressive strength. However, the flexural and 
tensile strength, the bond with steel reinforce- 
ment, and the resistance to wear are in general 
governed by the same factors that govern the 
compressive strength. The compressive strength, 
therefore, may be used as an indication of these 
other qualities and, since the test for compres- 
sive strength is comparatively simple, it is the 
test that is most often adopted. 

DURABILITY— If structures are to give long ser- 
vice, the durability of the materials is just as 
important as the strength. In the past this has 
not been fully appreciated and too much empha- 
sis has been placed on strength and economy 
alone. The most important factor affecting dura- 
bility of exposed concrete is its waterproofness. 
A concrete that will stand up for a long time re- 
quires sound, durable aggregates thoroughly 
incorporated in a waterproofed cement paste. 

ECONOMY— While economy of materials is im- 

portant, there are other factors affecting the 
economy of concrete which should receive more 
consideration. The amount of labor required in 
placing and finishing concrete is a considerable 
item in the total cost. Labor cost is lowest when 
the mixture used is most easily placed. The ease 
of placing varies with the plasticity of the mix. 
The most economical concrete is not the mix 
having the lowest cement factor nor the mix 
with the lowest cost for materials, but is the mix 
for which total cost— materials, handling and 
placing— is the lowest. 

WORKABILIT Y-The workability required varies 
with different classes of work and is determined 
by the methods of transporting and the details 
of placing— width and depth of forms and spac- 
ing of reinforcement. Plastic concrete may be 
regarded as a mass of aggregate particles, indi- 
vidually floated in a cement paste. This gives a 
mass that can be transported without segrega- 
tion and can be placed easily in such a manner 
that when the forms are removed the hardened 
concrete will have smooth surfaces, free from 
honeycombing. Concrete of such consistency 
requires a minimum amount of finishing. In 
much of the practice in the past, such concrete 
has not been obtained. This was largely due to 
the fact that arbitrary mixtures were specified 
which did not permit adjustments in the mix to 
suit the character of materials, the condition in 
which they were measured or the placing re- 
quirements of the job. In the endeavor to obtain 
workable mixtures, excess water was often 
added which almost invariably resulted in seg- 
regation, porosity and low strength. For direc- 
tions on how to avoid these faults, see sub-heads 
"Water" and "Mixing" under Specifications on 
page 20. 

UNIFORMITY- Uniformity is important since all 
parts of a structure designed for the same strength 
should be made of concrete of the same quality. 
Moreover, the best economy can be obtained only 
by the use of uniform batches of concrete. Uni- 
formity is best secured by using plastic concrete 
made homogeneous by thorough mixing of uni- 
formly measured quantities of materials. 

(Upper Left) 1910 Pittsburgh Natatorium, Pitts- 
burgh, Pa., F. A. Burden, New York. N. Y., Engineer. 
Grosvenor Atterbury, New York, N. Y., Architect. 
(Center Lefl) 1917 Inland Steel Company, Indiana 
Harbor, Ind. Entrance to tunnels connecting Com- 
pany's Plants No. 1 and No. 2. Brownell Improve- 
ment Co., Chicago, 111., General Contractors. 

(Lower Lefl) 1924 Northland Hotel, Green Bay, Wis. 
Martin Tullgren 6 Sons, Milwaukee, Wis., Architects. 
Tudolt, Hansen Const., Green Bay, Wis., Cement Work. 

(Upper Right) 1923 Hotel Retlaw, Fond du lac. Wis. 
Martin Tullgren & Sons, Milwaukee, Wis., Architects. 
The Immel Const. Co., Fond du lac. Wis., Contractors. 

(Center Right) 1918 Basement, Tr eleven Depart- 
ment Store Building, Fond du Lac, Wis. 

(Lower Right) 1922 Municipal Administration 

Building, Kaukauna, Wisconsin. W. E. Reynolds, 

Green Bay, Wisconsin, Architect. John Cop pes, 

Kaukauna, Wis., Contractor. 

WATERPROOFING Concrete and masonry below grade level 

An actual photograph of a damp basement. The use of Medusa Water- 
proofed Gray Portland Cement would have prevented this condition. 

The above photograph was taken in a "typical" 
damp or wet basement. This condition could 
easily have been prevented had Medusa Water- 
proofed Gray Portland Cement been used in the 
concrete and mortar, and in exterior and interior 
plaster coats. The exterior of all basement walls, 
in fact any concrete or masonry below grade is 
subject to ground water, ground acids and earth 
dampness. The use of Medusa Waterproofed 
Gray Portland Cement prevents wet basements. 

Monolithic concrete construction for basement 
walls and floors has many advantages over 
other methods. The use of Medusa Waterproofed 
Gray Portland Cement with this type of construc- 
tion gives a waterproofness to the basement be- 
cause a water repellent substance is incorpo- 
rated integrally throughout the entire mass of 
the concrete. The advantage of mill mixed water- 
proofed cement containing the proper amount 
of waterproofing uniformly distributed through- 

out the cement can be secured by specifying 
and using Medusa Waterproofed Gray Port- 
land Cement. 

PRECAST UNITS-When brick, stone or tile is 
used as the construction unit for the wall, it is 
imperative that these precast units be laid in a 
mortar made with Medusa Waterproofed Gray 
Portland Cement (see mortar specifications). 
When concrete block is used, the blocks should 
likewise be manufactured with Medusa Water- 
proofed Gray Portland Cement and laid up with 
waterproofed mortar made with Medusa Water- 
proofed Gray Portland Cement according to 
mortar specifications. 

Waterproofing is particularly recommended for 
all types of below grade construction such as 
swimming pools, elevator pits, mine shafts, base- 
ment caissons, etc. Medusa Waterproofed Gray 
Portland Cement should be used for all these 
types of construction and in fact, all concrete 
and masonry below grade. 


PROTECTING above grade level concrete, masonry 
and stucco surfaces against disintegration 

All above grade construction, whether it be of 
concrete, stucco, brick, cinder blocks, concrete 
bricks or any other type of masonry, should be 
protected by waterproofing, especially if it is 
exposed to the elements. 

There are many causes of disintegration of ex- 
posed surfaces. The freezing and the thawing 
action of water absorbed by exposed surfaces is 
very destructive and causes disintegration and 
spoiling. The force exerted by the freezing of con- 
fined water will break open a cannon ball. This 
same terrific force is exerted when water ab- 
sorbed into the pores and crevices of a wall 
freezes. This may open up mortar joints and 
leaky mortar joints permit the entrance of mois- 
ture, destroying interior decorations and creat- 
ing very unpleasant conditions. 

Frequently acid fumes of the air combined with 
rain water become a disintegrating factor when 
absorbed into masonry, stucco or concrete walls. 
Unwaterproofed mortar is a factor in the appear- 
ance of white efflorescence which gives an un- 
sightly appearance to masonry walls. It is 
caused by absorbed water dissolving alkali 
salts and then depositing them on the surface 
when the water evaporates. The use of Medusa 
Waterproofed Gray Portland Cement in stucco, 
concrete, concrete bricks, blocks as well as in 
mortar for laying up these and other masonry 
units will prevent absorption of water through re- 
pelling all water at the surface, thus stopping dis- 
integration and efflorescence and prolonging the 
life of concrete and masonry indefinitely. The 
cost of waterproofing with Medusa Water- 
proofed Gray Portland Cement is very small and 

is only a fraction of the expense necessary in 
maintaining and repairing leaky, damp, above 
grade construction, consequently it is advis- 
able to waterproof the original construction. 

Dollar Savings & Trust Company Building 

Press C. Dowler. Architect D. T. Riitle. Pittsburgh, Pa., Contractor 

Hillside Stone & Supply Co.. Pittsburgh 

Medusa Waterproofed Gray Portland Cement used m all the brick mortar 


SPECIFICATIONS for waterproofing concrete 
foundation walls and basement floors 

PORTLAND CEMENT-To insure the uniformity 
of the waterproofed cement, specify and use 
Medusa Waterproofed Gray Portland Cement. 

PROPORTIONS— The concrete shall be mixed in 
the proportions of one sack of Medusa Water- 
proofed Gray Portland Cement, two and one-half 
cubic feet of fine aggregate, and three to four 
cubic feet of coarse aggregate. 
Where concrete must resist moisture or damp- 
ness, the mix should never be any leaner than 
1:2:4. Leaner mixes are more porous, being less 
dense than the richer mixes. 
The richer mixes should be used where greater 
strength is required or where the exposure to 
water is quite severe, such as sea water work, 
swimming pools, large tanks or reservoirs. 
AGGREGATE-Fine aggregate shall consist of 
sand or screenings from crushed rock or pebbles, 
well graded from fine to coarse, passing, when 
dry, a screen having four meshes to the linear 
inch. Fine aggregate shall not contain injurious 
amounts of vegetable or other organic matter. 

Coarse aggregate shall consist of hard crushed 
rock or gravel, free from vegetable or other 
organic matter, and shall be free from soft, flat or 
elongated particles. It shall be well graded from 
l A inch to one inch in size, not more than fifteen 
per cent passing a screen having four meshes 
per linear inch. 

WATER-Jusi enough water should be used in 
mixing the concrete as will give a plastic, work- 
able consistency which can be economically 
placed. An excess of water must be avoided. It 
is recommended that not more than six gallons 
of water be used per sack of cement. 

MIXING-Medusa Waterproofed Gray Portland 
Cement is used in a concrete mixer exactly the 
same as regular portland cement. However, 
proper mixing is made easier by pulling Iwo or 
three gallons of water in the mixer before the 

aggregate and cement are put in. The minimum 
mixing time per batch is one and one-half min- 
utes. The cement contains the proper percentage 
of waterproofing. The contractor must not use 
any more gauging water than will give a jelly- 
like or mushy concrete. Concrete containing 
sufficient water lo permit a settling or segrega- 
tion of the heavier ingredients shall be rejected. 

SPADING— Concrete must be thoroughly spaded 
into place, well around reinforcing steel and 
against the forms, so as to secure maximum 
density by forcing out air and breaking up water 
and stone pockets, preventing honeycombed 

CURING-A11 concrete should be kept wet con- 
tinuously for a period of at least seven days. 
Unlike regular cement, once waterproofed ce- 
ment dries out it repels all water at the surface, 
hence cannot be wel again for proper curing. 

FLOORS-Where two-course basement floors 
are to be used the slab should be thick enough 
and sufficiently reinforced to resist the upward 
pressure of any water that may gather under 
the floors. Concrete should be no leaner than a 
1:2:4 proportion, mixed with a minimum amount 
of water and properly placed upon a well 
tamped cinder or rock fill which has been satu- 
rated before the concrete is poured. 

Whether the 1" or 2" finished topping of a two- 
course floor should be waterproofed will depend 
upon the use the floor will have. Oftentimes it is 
sufficient lo waterproof only the slab. 

For lopping see page 14, Specifications tor 
bonded Concrete Floor Finish. 

Where water conditions surrounding a house or 
building are not taken care of by drain tile, the 
concrete floors should be reinforced with steel 
bars, wire mesh or expanded metal mesh suffi- 
ciently to overcome lhe pressure of water which 
may gather under the floor. 




















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SPECIFICATIONS foi bonded concrete floor finish 

BASE SLAB— The surface of the structural base 
slab shall be finished reasonably true and struck 
off at a level not less than one inch below the 
required finish grade. 

As soon as the condition of the concrete base 
permits and before it has fully hardened, all dirt, 
laitance and loose aggregate shall be removed 
from the surface by means of a wire broom, 
which shall leave the coarse aggregate slightly 
exposed, or the surface otherwise roughened to 
improve bond with the lopping. 
When impossible to remove laitance and rough- 
en slab, surface shall be cleaned and prepared 
for bond by chipping after base has hardened, 

Just prior to placing the finish, the base slab 
shall be thoroughly cleaned by scrubbing, to the 
satisfaction of the engineer. 
PORTLAND CEMENT-Portland cement shall be 
Medusa Waterproofed Gray Portland Cement. 

AGGREGATES-Boih fine and coarse aggregates 
shall be used in the finish. Fine aggregates shall 
consist of clean, hard sand or crushed stone 
screenings free from dust, clay, loam or vegeta- 
ble matter. All particles shall pass a Vi-inch 
sieve and shall be graded from fine to coarse 
with the coarse particles predominating. Not 
more than five per cent shall pass a 100-mesh 
sieve and not more than 15 per cent shall pass 
a 50-mesh sieve. 

Coarse aggregate shall consist of clean, hard 
gravel or crushed stone free from dust, clay, 
loam or vegetable matter and from coatings 
which shall tend to weaken the bond. It shall con- 
tain no soft, flat or elongated fragments and shall 
be graded from Ve to 3 /e inch with not less than 
95 per cent passing a 3 /e inch mesh sieve and not 
more than 10 per cent passing a No. 8 sieve. 

All aggregate shall be selected with care. 
Coarse aggregate shall be of an approved 
character and samples of proposed material 
shall be submitted to the engineer for ap- 
proval prior to use. 

MIXTURE-The mixture shall be one part of 
Medusa Waterproofed Gray Portland Cement, 
one pari of fine aggregate and two parts oi 
coarse aggregate by volume. This nominal mix 
may be slightly varied, depending upon the local 
conditions and as the engineer may direct. If the 
aggregate is very coarse, the gravel or stone 
may be reduced, but in no case shall the volume 
of the coarse malenal be less than 1 1 2 times the 
volume of the fine. 

The mixture shall be determined by the engi- 
neer and once established shall not be changed 
except upon his written order. 

Not more than five gallons of mixing water, in- 
cluding the moisture in the aggregates, shall be 
used for each sack of portland cement in the 

Mixing of the concrete shall continue for at least 
two minutes after all ingredients are in mixer. 

CONSISTENCY-The concrete shall be of the 
driest consistency possible to work with a saw- 
ing motion of the strike-off board, or straight- 
edge. Changes in consistency shall be obtained 
by adjusting the proportions of fine and coarse 
aggregate within the limits specified. In no case 
shall the specified amount of mixing water 
be exceeded. 

shall be thoroughly wetted just prior to the plac- 
ing of the finish, but there shall be no pools of 
water left standing on the wetted surface. A thin 
coat of neat cement grout shall be broomed into 
the surface of the slab for a short distance ahead 
of the topping. The wearing course shall be im- 
mediately applied before the grout has hard- 
ened, and brought to the established grade with 
a straightedge. After striking off the wearing 
course to the established grade, it shall be com- 
pacted by rolling or tamping, and then floated 
with a wood float or power floating machine. 
The surface shall be tested with a straightedge 
to detect high and low spots, which shall be 

followed by steel troweling after the concrete 
has hardened sufficiently to prevent excess fine 
material from working to the surface. The finish 
shall be brought to a smooth surface free from 
defects and blemishes. No dry cement nor mix- 
ture of dry cement and sand shall be sprinkled 
directly on the surface of the wearing course 
to absorb moisture or to stiffen the mix. After the 
concrete has further hardened, additional 
troweling may be reguired. This shall be done 
as may be directed by the engineer. 

Note: Surfaces to be ground shall be swept with 
soft brooms after rolling to remove any water 
and surplus cement paste that may be brought 
to the surface. The wearing course shall then be 
floated and once lightly troweled, but no attempt 
shall be made to remove all trowel marks. 


FINISHING BY GRINDING-After the wearing 
course has hardened sufficiently to prevent dis- 
lodgemeni of aggregate particles, it shall be 
ground down with an approved type of grind- 
ing machine shod with free, rapid-cutting carbo- 
rundum stones to expose the coarse aggregate. 
The floor shall be kept wet during the grinding 
process. All material ground off shall be re- 
moved by squeegeeing and flushing with water. 

Air holes, pits and other blemishes shall then be 
filled with a thin grout composed of one part of 
No. 80 grain carborundum grit and one part of 
portland cement. This grout shall be spread over 
the surface and worked into the pits with a steel 
straight-edge, after which the grout shall be 
rubbed into the floor surface with the grind- 
ing machine. 

After all patch fillers have hardened for seven 
days, the floor surface shall receive a second or 
final grinding to remove the film and to give the 

finish a polish. It shall then be thoroughly 
washed and all surplus material removed. 
CURING AND PROTECTION-A11 freshly placed 
concrete shall be protected from the elements 
and from all defacement due to building oper- 
ations. The contractor shall provide and use tar- 
paulins when necessary to cover completely or 
enclose all freshly finished concrete. 
If at any time during the progress of work the 
temperature is, or in the opinion of the engineer 
will, within twenty-four hours, drop to 40 degrees 
Fahrenheit, the water and aggregale shall be 
heated and precautions taken to protect the 
from freezing for at least three days. 
As soon as the concrete has hardened to pre- 
vent damage thereby, it shall be covered with at 
least one inch of wet sand, or other covering 
satisfactory to the engineer, and shall be kept 
continually wet by sprinkling with water for at 
least seven days. 

WATERPROOFING mortar for masonry 

SPECIFICATIONS-The following specifications 
have been used on many buildings with per- 
fectly satisfactory results. 

The Waterproofed Portland Cement mortar shall 
consist of: 

1 pari Medusa Waterproofed Gray Portland 

3 parts clean, well-graded mason's sand 

10 pounds hydrated lime per bag of cement, 
or one-fifth part by volume of the cement 

MIXING-If a contractor has the proper equip- 
ment he will find it quite advantageous to have 
his batches of mortar mixed ahead of time, using 

just enough water in the preliminary mix to 
make a damp earth consistency and allowing 
Ihis mortar to set for any period of time up to one 
hour after the mixing, and then when required 
for use, more water is added to bring the mortar 
to the proper consistency. 

It has been found that mortar mixed in this way 
has greater plasticity and workability than 
freshly mixed mortar, as well as a greater ulti- 
mate strength. 

The increased workability and plasticity in the 
mortar enables the mason to lay a greater 
number of bricks in a given time than where 
freshly mixed mortar is used, and this saving 
in labor overcomes the slight expense involved 
in running two mixing boxes. 

Valley Stream High School Long Island, Frederick P. Wiedersum, Valley Stream, N. Y., Architect. Zerbe 
Construction Co., New York City. Medusa Waterproofed Gray Cement used throughout brick work. 


Allied Arts BIdg.. L ynch b li; I Weduso fa) 
Gray PortlandCement used in /c.::^"-'« — 

(Upper Left) Swimming pool at ha 
Crosse. Wis. Nelson & Fuisch, Archi- 
tects. Constructed by National Build- 
ers Inc., Minneapolis. One cor of 
Waterproofed White Portland Cement 

(Center Left) Girls' Dormitory, Uni- 
versity ot Michigan. Ann Arbor. Mich. 
Contractor, Pehison Bros.. Minneapo- 
lis, Minn. Dealer, W. H. L. Rohde, Ann 
Arbor. Mich. 8 cars of Medusa Water- 
proofed Gray Portland Cement used. 

mm] ■ 

dower Left) Anthony Wayne Hotel 
Hamilton, O. Contractor, F. K. Vaughn 
Bldq. Co. Architects. Fred G. Mueller 
6 Walter R. Hair, Assoc., Hamilton. 
Medusa Waterproofed Gray Portland 
Cement used. 







irg. Va. Medusa Waterproofed 
tnfbundations and retaining walls. 

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Lambert, Barger & B-anaman Building, Waynesboro, Virginia 

C. W. Hinnant, Lynchburg, Architect W. K. Smith, Jr., Associate Architect 

H. S. Brooks, Waynesboro, Contractor Lambert Mfg. Co., Waynesboro, Dealer 

Medusa Waterproofed Gray Portland Cement used. 

Carl Hansen Laboratory, West Allis, Wisconsin 

W. H. Buemming, Arch., Milwaukee, Wis. Osthoft & Peterson, Engs., Milwaukee 

W. W. Oeflein, Inc., Contractor, Milwaukee, Wis. 

Tews Lime & Cement Co., Dealers, Milwaukee, Wis. 

Medusa Waterproofed Gray Portland Cement used. 

American Telephone and Telegraph Co. Repealer station, Ridgeville, Ohio 

Mills, Rhines, Bellman & Nordjott, Architects, Toledo, Ohio 

W. J. Schirmer Co., Contractors. Cleveland, Ohio 

Medusa Waterproofed Gray Portland Cement used in all floors, 

foundations and for brick mortar. 

Swimming pool, H. S. Black Estate, Mansfield, Ohio 

Allhouse & Jones, Architects The Jacob Wolf Co., Contractors 

Builders Supply Co., Dealers 

Medusa Waterproofed Gray Portland Cement used. 


SPECIFICATIONS ioi waterproofed Portland Cement Stucco 

The following fundamental rules must be ob- 
served in ihe production of good stucco: 

a— Use a good rigid base which will not shrink, 
warp, bend or deteriorate with time. 

b— Use proper proportions and carefully selected 
sand and aggregates of correct grading. 

c— If an absorbent base, such as hollow tile, con- 
crete block or brick is used, sprinkle before 
applying fresh stucco. 

d— All stucco coats— base or scratch coal, second 
or brown coat, third or finish coat— should be 
waterproofed. This is just as important in the 
case of the base coat as any other, since the 
base coat must not possess sufficient "suc- 
tion" or absorptive tendency to take up the 
water from the fresh cement plaster or stucco 
coat applied to it before the cement has had 
an opportunity to hydrate and set. 

e-Each stucco coat must be sprinkled with 
water before applying the next coat; and the 
finish coat must be kept evenly moist by 
sprinkling. In hoi weather the work must be 
shielded from the direct rays of the sun, and 
protected at all times from the wind. The im- 
portance of these precautions cannot be over- 

l.DESIGN-Whenever the design of the struc- 
ture permits, an overhanging roof or similar pro- 
jection is recommended to afford protection to 
the stucco. It is well for the architect to prevent 
concentration of water flow getting at the stucco 
at all, so as to avoid staining of ihe finish. Stuc- 
coed copings, cornices, and other exposed hori- 
zontal surfaces should shed water quickly, and 
whenever departure from the vertical is neces- 
sary (at water tables, belt courses, and the like) 
the greatest possible slope should be obtained. 
Stucco should not be run to ihe ground-but 
should have a water table or belt course which 
is high enough above ihe ground io avoid 
splashing of mud and diri upon the finished sur- 
face. The backing should be of tile, brick, stone, 
concrete or metal lath, providing good mechani- 
cal bond for the stucco. It must be thoroughly 
cleaned before plastering. 

2. FLASHINGS-Suitable flashing should be pro- 
vided over all door and window openings 
wherever projecting wood trim occurs. Wall 
copings, cornices, rails, chimney caps, etc., 

should be built of concrete, stone, terra cotta or 
metal, with water-tight joints and ample over- 
hanging drip groove or lip. 

If copings are set in blocks with mortar joints, 
continuous flashing should extend across the 
wall below ihe coping and project beyond, form- 
ing an inconspicuous lip over the upper edge 
of ihe stucco— or the copings may be set in mor- 
tar composed of Medusa Waterproofed Portland 
Cement and sand. Continuous flashing with 
similar projecting lip should be provided under 
brick sills. This flashing should be so installed 
as to insure absolute protection against in- 
terior leakage. 

Cornices set with mortar joint should be pro- 
vided with flashing over the top or set in mortar 
composed of Medusa Waterproofed Portland 
Cement and sand. Sills should project well from 
ihe face of ihe stucco and be provided with drip 
grooves or flashings as described above for brick 
sills. Sills should also be provided with stools or 
jamb seals to insure wash of water over ihe face 
and not over ihe ends. 

Special aitenlion should be given io ihe design 
of gutters and downspouts at returns of porch 
roofs where overflow would result in discolor- 
ation and cracking. A two-inch strip should be 
provided at ihe intersection of walls and sloping 
roofs and flashing extended up and over it, ihe 
stucco being brought down to ihe top of the strip. 


All roof gutters should be fixed and downspout 
hangers and all other fixed supports should be 
put in place before the plastering is done, in 
order io avoid breaks in the stucco. All trim 
should be placed in such manner thai it will 
show its proper projection in relation to the fin- 
ished stucco surface, particularly in overcoating. 

MATERIALS-The cement for ihe first coat (base 
or scratch coat) and second (or brown coat) shall 
be Medusa Waterproofed Gray Portland 
Cement, or, if standard Gray Portland Cement 
conforming to the specifications of the American 
Society for Testing Materials be used, add two 
per cent by weight of Medusa Waterproofing 
Powder (2 lbs. per sack of cement) or Medusa 
Concentrated Waterproofing Paste (0.6 lb. per 
sack of cement). (See instructions on container.) 

The cement for ihe third or finish coat shall be 
Medusa Waterproofed White Portland Cement. 


4. FINE AGGREGATE-Fine aggregate shall 
consist of sand, or screenings from crushed stone 
or crushed pebbles, evenly graded from fine to 
coarse, passing when dry a No. 8 screen. Fine 
aggregates should preferably be of siliceous 
materials, clean, coarse and free from loam 
vegetable or other deleterious matter. 

5. HYDRATED LIME-Hydrated lime shall meet 
the requirements of the standard specifications 
for hydrated lime of the American Society for 
Testing Materials. 

6. COLORING MATTER-Only permanent, lime- 
proof and sunproof colors shall be used. Finish 
coats containing colors shall be applied as dry 
as possible to prevent separation of the colors. 
The use of Medusa Waterproofing will prevent 
the gradual fading of a color surface due to a 
film of efflorescence on the surface. 

7. WATER-Water shall be clean, free from oil, 
acid, strong alkali or vegetable matter. 

ingredients of the mortar shall be mixed until 
thoroughly distributed and the mass is uniform 
in color and homogeneous. The quantity of water 
necessary for the desired consistency should be 
determined by trial, and thereafter measured in 
proper proportion. The water shall be added 
slowly to the dry mix so as to allow the aggre- 
gates to absorb as much as possible in the course 
of mixing. 

9. MACHINE MIXING-The mortar shall prefer- 
ably be mixed in a suitable mortar mixing ma- 
chine of the rotating drum type. The period of 
machine mixing shall be not less than three 
minutes after all the ingredients are introduced 
into the mixer. 

10. HAND MIXING-The mixing shall be done in 
a watertight mortar box, and the ingredients 
shall be mixed dry until the mass is uniform in 
color and homogeneous. The proper amount of 
water shall then be added and the mixing con- 
tinued until the consistency is uniform. 


measurement of the proportions of water shall 
be used which will secure separate uniform 
measurements at all times . All proportions 
stated shall be by volume. A bag of cement (94 
lbs. net) may be assumed to contain one cubic 
foot. Forty pounds may be assumed as the 
weight of one cubic foot of hydrated lime. 


12. RETEMPERING-Mortar which has begun to 
stiffen shall not be used nor reiempered with 
additional water and used. 

13. CONSISTENCY-Only sufficient water shall 
be used to produce a good workable consistency. 
The less water in the mix, the better the quality 
of the mortar, within working limits. 


coats shall be one pari Waterproofed Portland 
Cement (white or gray) and three parts fine ag- 
gregate; hydrated lime for buttering purposes 
not to be in excess of 10% by weight of the 
cement used. 

15. APPLICATION-The plaster shall be applied 
with a steel trowel and carried on continuously 
in one general direction without allowing the 
plaster to dry at the edge. If it is impossible to 
work the full width of the wall at one time, the 
jointing shall be at some natural division of the 
surface, such as a window or a door. 

The first coat shall thoroughly cover the base on 
which it is applied and shall be troweled enough 
to insure the best obtainable bond. Before the 
coat has set it shall be heavily cross-scratched 
with a saw-toothed metal paddle or other suit- 
able device to provide a strong mechanical key. 

The first coat shall be kepi thoroughly wet until 
the second coat is applied. The second coat shall 
be brought to a true and even surface by screed- 
ing at intervals not exceeding five feet, and by 
constant use of straightening rod. 

When the second coat has stiffened sufficiently. 
it shall be dry floated with a wood float, and 
evenly cross-scratched to form a good mechani- 
cal bond for the finish coat. 

From the time of application of the second coat 
and for not less than three days thereafter, the 
stucco must be kepi continuously wet by thor- 
ough spraying ai frequent intervals. It shall then 
be allowed to dry out ihoroughly. 

The finish coat shall be applied not less than 
a week after the application of the second coat. 
Methods of application will hereinafter be de- 
scribed under "Finish." 

16. CURING-To develop maximum strength and 
density in any Portland Cement product it is 
necessary to cure it properly. This is especially 
true of Portland Cement stucco, which is really 
a thin slab of concrete. Each coat should be kept 
damp continuously for at least two days. Mois- 
tening should commence as soon as the stucco 


«*> H„ide„c. o/ S. Goodman, (Cant.,) i^-S J- »-» ** STSff-SS^*^ 
Highland Par*, /]/. E. H. flabe, and E. Hou.a, Clinton. ******** %**£*** **«*. MM Ban- 

(Bottom Right) JtaiJdanca of Harbor* 
Holmqt—n, San Antonio. Tow. MvrrlM 
£ Hoonan, ArcaJJoclf . F. O. Holtiman, 

Cement used lor exterior ttueco. Gray & Whlto Portland Comon/i mod. 

umd tot i/ucco. 

(Top) Masonic Home, Wichita, Kan. (Center Left) Residence ox A. G (C#nt«r Hini,»\ «.. ■ -i .. „ «„., 
Hi/on & Githens. Architects. New c^ Gienco# Winoia . ° r * (Cen e r H»ght) The Anderson Memo- (Bottom) flesidence of James N- fiw- 
v^-l u v « . - — i*aoie, Lriencoe, Illinois. Adler and rial in La r»u M tin. r\**- * **__ _ - 

George H. Siedhoff Cons/ruciion Co.. Work ' * "J 1111 *- ^^ *&%*. Win- man. La Crosse, Archirecf. TTieo. /. Wes/er GeneFa' W Y. Plaster Con- 

Gray Waterproofed Cements used in 
the srucco. 

used in srucco. 

Cement used in stucco. 


has hardened sufficiently not to be injured, ap- 
plying the water in a fine fog spray. Avoid 
soaking the wall. Give it only as much water as 
will be readily absorbed. To prevent excessive 
evaporation on the sunny or windward sides of 
building in hot, dry weather, tarpaulins should 
be hung over the outside of the stucco and 
kept moist. 

After the damp-curing period, the base coats 
should be allowed to dry thoroughly before the 
finish coat is applied. The practice of doubling 
coats without a two-day moist-curing period fol- 
lowed by a drying interval is not good construc- 
tion practice. Unlike regular cements, once 
waterproofed stucco dries out it repels all water 
at the surface, hence cannot be wet again for 
proper curing. 

When stucco is applied during cold weather, 
longer curing periods are necessary. In freezing 
weather it should not be applied unless special 
methods are employed to keep the materials at 
a temperature above 50 degrees Fahrenheit for 
at least 48 hours. 

FINISH- 17. Stippled-The finishing coat should 
be troweled smooth with a metal trowel with as 
little rubbing as possible, and then should be 
lightly patted with a brush of broom straw to 
give an even stippled surface. 

18. Sand Floated-The finishing coat, after being 
brought to a smooth, even surface, should be 
rubbed with a circular motion of a wood float 
with the addition of a little sand slightly to 
roughen the surface. This floating should be 
done when the mortar has partly hardened. 

19. Sand Sprayed— After the finishing coat has 
been brought to an even surface, it should be 
sprayed by means of a wide, long-fiber brush— 
a whiskbroom does very well— dipped into a 
creamy mixture of one part of cement to two or 
three parts sand, mixed fresh at least every 
thirty minutes and kept well stirred. This coating 
should be thrown forcibly against the surface to 
be finished. This treatment should be applied 
while the finishing coat is still moist and before 
it has attained its early hardening-thai is, 
within three to five hours. To obtain lighter 
shades, add hydrated lime not to exceed 10% 
of the weight of the cement. 

20. Rough-cast or Spatter Dash-After the finish- 
ing coat has been brought to a smooth, even sur- 
face with a wooden float, and before finally 
hardened, it should be uniformly coated with a 

mixture of one sack of cement to two or three 
cubic feet of fine aggregate wet to the consis- 
tency of cream, and thrown forcibly against it to 
produce a rough surface of uniform texture when 
viewed from a distance of 20 feet. 

Special care should be taken to prevent the 
rapid drying out of this finish by thorough wet- 
ting down at intervals after stucco has hardened 
sufficiently to prevent injury. 

21. Cement Colors— When it is required that any 
of the above finishes should be made with col- 
ored mortar, not more than 10% of the weight of 
portland cement should be added to the mortar 
in the form of finely ground mineral coloring 
matter and this quantity should replace an equal 
amount of hydrated lime, instead of cement, or 
used as an additional material. 

A predetermined weight of color should be add- 
ed dry to each batch of dry fine aggregate be- 
fore the cement is added. The color and fine 
aggregate should be mixed together and then 
the cement mixed in. 

The whole should be then thoroughly mixed dry 
by shoveling from one pile to another through 
a Vi-inch mesh wire screen until the entire batch 
is of uniform color. Water should then be added 
to bring the mortar to a proper plastering 


Concrete Blocks, Concrete Surfaces, 

TUe and Brick 

TILE-Tile shall be hard burned with dovetail or 
heavy ragged scoring. Joints are not to be raked, 
but cut back to the surface of tile. 

Surface of tile shall be brushed free from all 
dirt, dust and loose particles, and, prior to ap- 
plication of stucco, shall be wet to prevent suc- 
tion and absorption. 

BRICK-Brick shall be rough hard burned brick, 
set with %-inch joints. Joints to be raked out V2- 
inch from face of brick. Surface of brick shall be 
brushed free from all dirt, dust and loose parti- 
cles, and prior to application of stucco, shall 
be wet. 

Old brick walls which are to be overcoated shall 
have all loose, friable or soft mortar removed 
from the joints to a depth of at least half an inch. 
Brick surfaces, painted or waterproofed, shall be 
covered with metal lath. 

Extremely soft brick must be covered with metal 
lath of fine poultry wire, well stapled. 


CONCRETE BLOCKS - Shall be rough and 
coarse, but not friable, and set in cement mortar, 
with joints raked out at least Vfe-inch deep. Sur- 
faces of blocks shall be brushed free from all 
dirt, dust and loose particles, and prior to ap- 
plication of stucco, shall be wet. 

CONCRETE SURFACES - Concrete surfaces 
shall be hacked or roughened by drills, so as to 
provide bond for stucco. 

After hacking, surface shall be washed down 
with a solution of one part muriatic acid to 10 
parts water. After acid solution has exhausted 
itself, surface is to be washed down, to remove 
any remaining acid. Wirebrush surface so as to 
remove all loose particles of concrete. 

Prior to application of stucco, wet the wall so as 
io prevent absorption of water from stucco, and 
apply a good creamy cement grout an hour be- 
fore applying stucco. 

SMOOTH SURFACES-To obtain a smooth sur- 
face, after troweled finish has become suffi- 
ciently hard, rub carefully with a fine carborun- 
dum stone and water, rinse with clean water, 
grout with clear cement and allow to remain for 
a week or longer; rub io smooth finish. 


Where Sheathing Is Used 
SHEATHING - Sheathing boards shall not be 
less than six inches nor more than eight inches 
wide, dressed on one or both sides io a uniform 
thickness of 13/16 of an inch; laid horizontally 
across wall studs, and fastened with not less 
than two 8d nails at each stud. 

Over sheathing boards shall be laid, in hori- 
zontal layers beginning at the bottom, a sub- 
stantial paper well impregnated with tar or 
asphalt. The bottom strip shall be laid over the 
baseboard at the bottom of the wall, and each 
strip shall lap the flashings at all openings. 

ing-Studs spaced not io exceed 16-inch centers 
should be run from the foundation io rafters with- 
out any intervening horizontal members. The 
studs should be tied together just below the 
floor joists with 1 x 6 inch boards which should 
be let into the studs on their inner side, so as to 
be flush, and securely nailed io them. These 
boards will also act as sills for floor joists, which 
should be securely spiked to the side of studs. 

BRACING-Corners of each wall shall be braced 

diagonally with 1 x 6 inch boards lei into studs 
on inner side, and securely nailed to them. 

In back-plastered construction in which sheath- 
ing is omitted at least once midway in each story 
height, the studs shall be braced horizontally 
with 2x3 inch bridging set one inch back of the 
face of the studs. This assumes thai the siuds are 
2x4 inches. Larger siges require larger bridging. 

FURRING-One-half inch 22 gauge crimped fur- 
ring is io be fastened direct to the studding, using 
1 Va inch by 14 gauge staples placed 12 in. apart. 

LATH— Expanded metal, or wire mesh, galva- 
nized or painted, weighing at least 3.4 pounds 
per square yard. 

Metal lath shall be placed horizontally, drawn 
tight, and attached with Wa inch by 14 gauge 
staples, or 6d nails driven to a penetration of at 
least 7 /s inch and bent io engage at least one rib, 
not over eight inches o. c. 

Lath shall be lapped at least two inches hori- 
zontally and tied with 18 gauge black tie wire 
at least once between studs. Vertical laps shall 
be at least two inches and shall occur at sup- 
ports. Lapped ends fastened with staples or 6d 
nails not over four inches o. c. 

CORNERS-The sheets of metal lath shall be 
folded around the corners for at least four inches 
and well stapled down in sheathed construc- 
tion and one siud opening in open frame con- 

Corner bead is not recommended, but a strip of 
diamond mesh expanded metal, 24 gauge, 
formed io a six inch angle, may be used. 

INSULATION-The air space in back-plastered 
walls may be divided by applying building 
paper, quilting, felt, or other suitable insulating 
material between the studs, fastening it to the 
studs and bridging by nailing wood strips over 
the folded edges of the maierial. This insulation 
shall be so fastened as to leave about one inch 
air space between it and stucco. Keep insulating 
material clear of stucco. Make tight joints 
against the framing. 

BACKING COAT-Shall be applied directly fol- 
lowing the completion of the brown coat. The 
keys of the scratch coat shall first be thoroughly 
dampened, and the backing coat well troweled 
on io insure filling spaces between keys and 
thoroughly covering back of lath. The backing 
coat shall provide a total thickness of plaster 
back of lath of % or Va of an inch. 


SPECIFICATIONS for waterproofing existing concrete work 



The old surface shall be mechanically rough- 
ened or hacked by means of stone mason's ham- 
mer, drills or similar tools, exposing the mairr- 
of the concrete and leaving Va inch to % inch 
deep holes every two to three inches, so as lo 
provide a better bond for the cement plaster. 

Remove all loosened pieces and apply freely to 
the cleaned area a solution of one part muriatic 
acid and ten parts of water, using a fibre or acid 
brush. Allow acid solution to remain until the 
acid exhausts itself, approximately 10 minutes. 

Wash the surface with water from a hose, being 
careful to remove all of the acid solution. Go 
over the walls with a stiff wire brush, or where 
available, compressed air or steam may be 
used, and remove any remaining loose pieces 
or particles. 

—Mortar joints shall be raked out to a depth of 
Vz inch to Va inch and all old and loose mortar 
removed. This is absolutely necessary in order 
to give good key for the plaster. Prepare a grout 
of Medusa Portland Cement and water. 

Mix to a creamy consistency and apply with a 
fibre brush to the cleaned surface, brushing with 

grout thoroughly into the concrete for a short 
distance ahead of the plaster. 

All masonry surfaces shall be thoroughly satu- 
rated with water before grouting is applied. 

REMOVING OLD PAINT-A11 oil paint films or 
whitewash must be thoroughly removed. 


PROPORTIONS-The cement plaster shall be 
composed of one part Medusa Waterproofed 
Gray Portland Cement and two and one-half 

parts sand. 

WATERPROOFING - If Medusa Waterproofed 
Cement is not available, use Medusa Water- 
proofing, either Powder or Concentrated Paste, 
to waterproof the portland cement employed. 
Follow the simple directions on the container. 

SAND— Shall be clean, sharp and free from clay, 
loam, vegetable or other injurious matter, \ a inch 
down in size. 

MIXING— Use materials as heretofore specified, 
mix the waterproofed cement plaster to a stiff, 
workable consistency, adding the water slowly, 
using the minimum volume of water necessary 
to give a plastic mix. 

Y. M. C. A. Building, Evanslon, Illinois 

Chester H. Walcott, Chicago, 111, Architect N. P. Severin Co., Chicago, Contractor 

Medusa Waterproofed Gray Portland Cement used in all concrete below grade and in swimming pool. 












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Seville School Ross Township, Pa. Press C. Dowlei, Pittsburgh, Pa., Architect Powell Bros., New Kensington, Pa., Contractors 
Medusa Walerprooted Gray Portland Cement used in brick mortar and foundation. 

WORK— If there is a continual seepage through 
the walls, holes must be bored in the walls and 
tubes or small gas pipes inserted to concentrate 
the flow of water and relieve the pressure while 
the plaster coat is being applied. Caulk around 
pipes with oakum or lead wool. Drainage pipes 
should remain open until the waterproofed 
cement plaster coat has thoroughly set and is 
capable of resisting the pressure by its own ad- 
hesive strength, after which remove pipes and 
plug holes, covering them with waterproofed 
cement plaster. 



rate the entire surface with water to prevent the 
surface from absorbing water from the cement 
plaster before the cement has had time to hy- 
drate or set. 

Apply the first coat of plaster 3 /s inch thick, 
troweling the plaster well into the surface so as 
to secure a proper bond. 

Scratch the first coat with a "scratcher." Do not 
use nails or trowels, nor scratch too deep. 

As soon as the first coat has set hard enough, 
sprinkle with water and apply the second coat 
3 /e inch thick, troweling the plaster with suffi- 
cient pressure to obtain maximum density and 
to close all surface pores, leaving a tight, clcse- 
grained finish. 

Where waterproofed cement plaster is to be ap- 
plied to walls and floors, cut second coat of 
plaster off six inches above the finished floor line. 

* After the piaster coat has been applied, 
applied to give better diffusion of light and 


Where joints must be made in cement plaster 
work, run the cement work an inch or two be- 
yond the contemplated joint. After plaster has 
set, cut this surplus off on as broad bevel as 
possible, giving this bevel a coat of grout prior 
to applying subsequent plaster. 
The finished surface must be protected from too 
rapid drying out, by keeping moist for at least 
a week to allow it to harden thoroughly and to 
prevent hair cracks. Sprinkle at frequent inter- 
vals with a hose, or cover with canvas or burlap 
kept continually wet.* 


FLOORS - Water gathering under basement 
floors exerts an upward pressure which often is 
strong enough to crack the concrete floor. 
If existing floors have been cracked by water 
under the floor, the waterproofed portland 
cement lopping applied to the lop of the old 
floor should be sufficiently reinforced to pre- 
vent cracking. 

walls have been plastered, prepare the surface 
of floors, including the six inch base at walls, in 
the same manner as walls (see "Preparation 
of Surface"). 

Have floors cleaned, saturated with waler and 
apply grout as described; use care to prevent 
mud or dirt being tracked over the grouted sur- 
face. Apply a two-inch coat of waterproofed 
cement jloor topping as per specifications for 
bonded concrete floor finish, page 14, joining 
the covered base wilh the finished wall cement 

Medusa Portland Cement Paint should be 
a washable surface that is easy to keep clean. 

SPECIFICATIONS foi waterproofing concrete blocks 
during the process of manufacturing 

The block manufacturer will find the following 
specifications of value. 

CEMENT— The cement used shall be Medusa 
Waterproofed Gray Portland Cement. 

COARSE AGGREGATE-Coarse aggregate shall 
consist of clean pebbles, crushed limestone, 
granite or trap rock, well graded so thai the 
largest size will not exceed one third of the thick- 
ness of the thinnest web of the block. Not more 
than five percent shall pass a Winch screen. 

FINE AGGREGATE-Fine aggregate shall con- 
sist of sand or screenings from hard crushed 
limestone, granite or trap rock, well graded and 
free from dust, which shall pass though a Vi-inch 
screen, and shall not contain more than five per- 
cent of silt, loam or impurities. It should have at 
least 15% retained on a Vs-inch screen. 

PROPORTIONS-The mixture of waterproofed 
cement, sand and stone must be such that the 
block will comply with the governing Building 
Code, whether city or state. In some states and 
cities this requirement is a compressive strength 
of not less than 750 pounds per square inch; in 
other localities the requirements are 1,000 
pounds or more. 

The block manufacturers should experiment 
with the sand and stone available until he can 
give the required strength with the least amount 
of cement per block. As an illustration, some 
manufacturers obtain 20 or 22 blocks with block 
size of 8" x 8" x 16" from one sack of cement, 
whereas others, due to poorly graded aggregate, 
cannot obtain more than 14 or 16 blocks per bag 
of cement. In general, the coarser the grading 
of aggregate the greater the strength for a given 
amount of cement provided the mix is workable 
in the machine. However, too coarse grading 
tends toward rough surfaces and edges. 

The mix for the facing on blocks shall consist 
of one part Medusa Waterproofed Gray Portland 
Cement and three parts of clean sand. 

HAND MIXING— Dampen the sand or aggregate, 
add the waterproofed cement, and mix as usual. 
When sand and waterproofed cement are uni- 
formly mixed, add only enough water to secure 
proper consistency. 

BATCH MACHINE MIXING-Put the sand and 
aggregate into the mixer with the waterproofed 
cement; allow mixer to run until the cement and 
sand are well mixed before adding additional 
water. Mix at least one and one half minutes 
after all water is added. In dry tamp method, 
mix at least two minutes. 

CONSISTENCY-Sufficent water shall be used 
to permit the blocks to be removed from the 
molds without distortion, but not so much as to 
cause sagging. 

CURING-A11 concrete blocks should be thor- 
oughly cured by keeping them in well built 
steam kilns, by keeping them wet by the use of 
fog sprays, or by sprinkling them often enough 
so surfaces will not become air-dry. 

Proper and thorough curing is one of the most 
essential and important steps in the manufac- 
ture of concrete blocks. 

Send for booklet on recommended practice for 
the manufacture of blocks. 

Residence of Miss Anna Zolter, St. Clair River, Detroit. 
Blocks supplied by State Builders Supply Co., Detroit. 


SPECIFICATIONS for the waterproofing of concrete 

brick and roofing tile 

The manufacture of concrete brick and concrete 
roofing tile has been increasing rapidly in the 
last few years. Manufacturers of complete 
equipment for making concrete brick and con- 
crete tile have established independently owned 
manufacturing units. 

Concrete brick and tile have the advantage of 
being lighter in weight, easier to handle and 
transport, and easy to lay up, permanent, beauti- 
ful and fireproof. They can be made in any range 
of colors, shades and textures or combinations, 
also in any size, thereby offering the builder or 
architect a wide variety to meet the needs 
in design. 

Because the materials for manufacturing con- 
crete brick and tile are universally available, the 
manufacturing plants can be erected in practi- 
cally any market, thereby saving tremendously 
on freight and trucking charges. 

SPECIFICATIONS-Aggregate used in concrete 
brick shall be hard and sharp. Grading should 
start with a 3 /s-inch mesh. About 5% should be 
left on a Vi-inch mesh, approximately 15% on a 
Va inch mesh, 15% on a 14-mesh, 25% on a 28- 
mesh, 30% on a 48-mesh, 10% on a 100-mesh. 

It is of course not necessary to adhere strictly 
to this gradation, for there are other variations 
as good but this principle applies to every kind 
of concrete unit. The better the aggregate is 
graded, the better the units will be. 

RATIO OF MIX-The ratio of mix is one part of 
Medusa Waterproofed White or Waterproofed 
Gray Portland Cement to seven parts of sand, 
up to one part of Waterproofed White or Water- 
proofed Gray Portland Cement to ten parts cf 
sand. Materials should be mixed with the water 
for four minutes. In cold weather the water 
should be warmed. To obtain the proper water 

content, a handful of mix, stroked with the 
trowel, should bring beads of moisture to the top, 

KILN CURING-Cement brick gets its initial set 
over night in store room. If cured in steam kilns, 
the starting temperature should be 70 °, and then 
run up to 100 or possibly 110°. Brick should be 
kepi in this temperature over night. Wet steam 
should be used at a low pressure of about five 
pounds. The amount of relative humidity should 
be at least 90%. 

WATER CURING-Brick should stand over night 
to get initial set, then pile in yard and wet down 
with a hose as necessary to keep them wet con- 
tinuously for at least ten days. Care should be 
taken in the summer time to see that bricks do 
not dry out too fast. Likewise in winter, care 
should be taken so bricks do not freeze together. 

The use of Medusa Waterproofed Gray or Water- 
proofed White Portland Cements in making con- 
crete brick and tile does not vary the specifica- 
tions. Waterproofed cements are used exactly 
the same way as ordinary gray cement. 

Waterproofed concrete brick repels all water at 
the surface and is particularly advantageous as 
a means of preventing efflorescence and disinte- 
gration. In unwaterproofed concrete, brick or 
tile, dirt accumulates on the surface, is carried 
by water when the latter is absorbed, into the 
surface. If waterproofed cements are used, the 
water laden with dirt cannot be absorbed into 
the surface, but the dirt itself is washed off. 
Waterproofing concrete brick also prevents de- 
terioration due to absorbed water entering liny 
crevices or pores, freezing, causing crumbling. 
All water is repelled at the surface. To prevent 
mortar deterioration, all concrete brick should 
be laid in mortar made with Medusa Water- 
proofed Portland Cement. 


Natural colored Dunbnk 
home in Atlanta, Georgia. 

Dunbrik is used in solid 
and hollow wall con- 
slmction, plain or faced. 


Buff mat glazed Dunbrik home 
with a green mat glazed 
Duntex roof, Metropolis, Illinois. 



A standard Gray Portland Cement guaranteed to comply with the specification requirements 
of the American Society for Testing Materials. 


Our standard Gray Portland Cement with the proper amount of Medusa Integral Water- 
proofing ground in at the mill It is less expensive than adding waterproofing on the job, and 
insures proper distribution. It should be used wherever concrete is below grade or exposed 
to moisture or dampness. 


High Early Strength Cement has all the properties of our standard Gray Portland Cement 
but with this difference-it has the normal 5 to 7 days' strength in 24 hours. 


A standard Portland Cement used wherever Portland Cement is specified and white or 
colored effects are desired-same strength as Gray Portland Cement-non-staining. 


Our standard White Portland Cement with the proper amount of Medusa Integral Water- 
proofing ground in during process of manufacture. Used for stucco and stone mortar and 
all work subjected to damp or wet conditions. Non-staining. 


A non-staining waterproofed mortar cement for setting, pargeting, and pointing of cut stone, 
and for laying up face brick. The cost permits use for mortar in backup wall. 


Has a Portland Cement base and is waterproofed. Obtains a high early strength which is 
very important to the mason contractor. It has a very pleasing color when used natural or 
with mortar colors. It is a prepared masonry mortar having minimum shrinkage; simply mix 
with sand and water on the job. 


A decorative and protective coating for all concrete and masonry surfaces. Can be applied 
on fresh concrete or wet surfaces. Furnished in black, white and seven colors. 


A concrete floor covering that needs no undersurfacer. It is moistureproof and highly resistant 
to abrasive wear, Furnished in black, white and six colors. 


A flat wall finish for interior use. Comes in white and seven beautiful colors, is durable, 

quick drying, economical. One coat is usually sufficient. 


A dry powder to be added to Portland Cement. By its use, concrete is waterproofed. It is to 
be used where Medusa Waterproofed Gray Portland Cement or Medusa Waterproofed 
White Portland Cement is not available. Powder is shipped in 40 lb. bags. 


Similar results are obtained as with the powder. It is added to the concrete mix through the 
gauging water. Paste is shipped in 8 lb. and 40 lb. containers. Also furnished in 225 lb. 
and 400 lb. drums. 



Why ihe Name Medusa 3 

Why Concrete, Stucco and Masonry, Including Mortar, Should be Water- 
proofed During the Original Construction 5 

Waterproofed Cement Has These Advantages . 6 

Proving the Value of Medusa Waterproofing . . 7 

Essentials of Good Waterproofed Concrete . . 8 

Waterproofing Concrete and Masonry Below Grade Level 10 

Protecting Above Grade Level Concrete, Masonry and Stucco Surfaces 
Against Disintegration 11 

Specifications for Waterproofing Concrete Foundation Walls and Basement 
Floors 12 

Specifications for Bonded Concrete Floor Finish 14 

Waterproofing Mortar for Masonry 15 

Specifications for Waterproofed Portland Cement Stucco 19 

Specifications for Waterproofing Existing Concrete Work 25 

Specifications for Waterproofing Concrete Blocks During the Process of 
Manufacturing 27 

Specifications for the Waterproofing of Concrete Brick and Roofing Tile . . 28 

The Twelve Medusa Products